The present invention relates to a replaceable ear wax guard for placement in an opening in a wall part of a housing of an in-the-ear hearing aid designed for positioning in the ear canal, comprising an essentially tubular element partially closed in one end by an ear wax retaining barrier.
In in-the-ear hearing aids where the hearing aid housing is placed within the user's ear canal with the acoustic outlet port facing the inner ear and connected to the telephone unit of the hearing aid, it is a well-known problem that the acoustic outlet passage is exposed to contamination with cerumen or ear wax which may lead to clogging of the acoustic outlet passage with consequently reduced sound reproduction. At worst, there may be a risk for the ear wax to enter the hearing apparatus housing and result in damage to the electrical components of the hearing aid.
In order to avoid this problem, it is known from U.S. Pat. No. 4,972,488 to arrange a replaceable ear wax barrier, which can at the same time provide a dampening of the acoustic response, in the acoustic outlet passage in the apparatus housing. In this known design, the ear wax barrier is formed as a screw plug the arrangement of which presupposes a thread being provided in the acoustic outlet passage, and the ear wax barrier is in the end facing outward at the insertion by screwing, designed with incisions for providing a slot for a screw driver. The barrier effect for retaining of ear wax is obtained by providing inward projections in a through-going cavity in the screw plug.
As a consequence of the very small dimensions where the acoustic outlet passage has typically a diameter of about 1 mm, the screw plug form entails that insertion and removal of the ear wax guard is a rather difficult operation, especially for weak-sighted hearing aid users, and the inward projections forming a kind of maze in the through-going cavity do not provide full security against migration of ear wax. Furthermore, the screw plug design cannot be used in in-the-ear hearing aids of the conventional type where the acoustic outlet passage is formed by a short hose or tube member connecting the telephone unit with an acoustic output port in the wall of the hearing aid housing.
Furthermore, the international patent application WO 84/04016 discloses an ear wax guard in the form of an outwardly closed plug with a disc-shaped head which at the placement of the plug covers the acoustic outlet port of the aid housing. In the plug under the disc-shaped head, there are provided radial acoustic passageways in connection with a longitudinal acoustic passageway opening in the plug end introduced in the aid housing. To secure a sufficient acoustic passage, the plug is designed such that the disc-shaped head is kept at a distance from the outside of the aid housing which entails a risk, albeit reduced, of migration of ear wax under the plug and in the narrow radial acoustic passageways. As a consequence of the smooth disc-shaped head, the insertion and removal of the plug is also in this case a difficult operation.
In a hearing aid known from U.S. Pat. No. 4,553,627, an essentially mushroom-shaped ear wax guard with a crossing acoustic passage is mounted with snap engagement in a metal ring inserted in the acoustic outlet port of the hearing aid housing.
In published European application EP 0724 377 A1, an ear wax barrier of the kind defined above is disclosed, which is inserted by press-fitting in the receiver tube of a hearing aid with frictional engagement between a lip provided by the wax barrier and the receiver tube. Thereby, removal or dislodging of the wax barrier will be resisted. Whereas the operation of removal is not described in the document the only possibility would appear to seize a projecting collar formed at the distal end of the wax barrier by a suitable instrument, such as a knife, a tongue or a pair of tweezers.
With this prior art as background, it is the object of the invention to provide a replaceable ear wax guard of the stated type with a simple and low-cost design suited for all kinds of in-the-ear hearing aids and which by use of an applicator can be mounted in and removed from the aid housing in a simple way.